#define _CRT_SECURE_NO_WARNINGS 1
#include<iostream>
#include<cmath>
using namespace std;
double dis(double xa, double ya, double xb, double yb)
{
	return sqrt(pow(xb - xa, 2) + pow(yb - ya, 2));
}
int main()
{
	double x1, y1, x2, y2, x3, y3;
	scanf("%lf%lf%lf%lf%lf%lf", &x1, &y1, &x2, &y2, &x3, &y3);
	double ans = dis(x1, y1, x2, y2) + dis(x2, y2, x3, y3) + dis(x1, y1, x3, y3);
	printf("%.2f\n", ans);
	return 0;
}